JP7363092B2 - Fixing device, image forming device, and control program - Google Patents

Description

The present invention relates to a fixing device, an image forming device, and a control program.

Fixing devices equipped with cleaning members are known. For example, in Patent Document 1, a sheet of paper onto which a toner image has been transferred is conveyed between a fixing roller and a pressure roller, and heated and pressed to fix the toner image onto the sheet of paper. A fixing device is disclosed that cleans toner adhering to the image forming apparatus. Toner that has spilled onto the fixing roller or the pressure roller is accumulated on the cleaning roller over time. Here, if the temperature of the fixing roller or the like becomes too high, the toner may melt, and the melted toner may flow back from the cleaning roller 21 to the pressure roller 13 or the fixing roller 12. In Patent Document 1, this issue is addressed, and in order to prevent this backflow, the image forming operation is stopped for a predetermined period of time when a predetermined number of sheets of paper are continuously recorded, and the fixing roller 12, pressure roller 13, and cleaning roller 21 are It has been proposed to cool down the device by rotating it for a predetermined period of time.

Japanese Patent Application Publication No. 2001-92292

In the case of a configuration in which toner is accumulated on a cleaning roller or the like as in Patent Document 1 mentioned above, there is a limit to the amount of accumulated toner. Therefore, if this limit is exceeded, there is a problem in that toner adhering to the fixing roller, pressure roller, etc. is not collected by the cleaning roller, etc., but adheres to the paper and stains the paper.

The present invention provides a fixing device, an image forming device, and a control program that suppress toner stains on paper compared to a case without a mode in which toner from a removal section that removes toner from a heating section is ejected onto paper. purpose.

The invention according to claim 1 is:
a fixing unit including a heating unit that sandwiches and heats the paper conveyed while holding a toner image; and a removal unit that removes toner from the heating unit; and a fixing unit that increases the temperature of the heating unit to a first temperature. a first control in which the sheet holding the toner image is sent to the heating section in a state in which the toner image is retained; and a second control in which the temperature of the heating section is set higher than the first temperature so that the toner held in the removal section is transferred to the heating section. A second time interval longer than the first time interval between adjacent sheets when the plurality of sheets of paper not holding a toner image are continuously conveyed in the first control in a state where the temperature is increased. The fixing device is characterized in that it includes a control unit that executes a second control for sending the image to the heating unit at time intervals .

The invention according to claim 2 is:
At the start of the second control, the control section applies a first amount of heat per unit time to the heating section such that the heating section is raised toward a third temperature higher than the second temperature. A claim characterized in that, midway through, the amount of heat per unit time given to the heating section is changed to a second amount of heat, which is lower than the first amount of heat, so that the heating section is adjusted to the second temperature. 1. The fixing device according to 1 .

The invention according to claim 3 is:
In the second control, after feeding a predetermined number of sheets of paper into the heating section, or if the paper runs out before reaching the specified number of sheets, the heating section is activated at the time when the paper runs out. 3. The fixing device according to claim 1 , further comprising a cooling period during which the fixing device is cooled.

The invention according to claim 4 is:
4. The fixing device according to claim 3 , wherein, in the second control, the control section feeds the paper to the heating section even during the cooling period.

The invention according to claim 5 is:
5. The fixing device according to claim 1, wherein the control unit does not start the second control if the paper runs out before starting the second control. .

The invention according to claim 6 is:
6. The method according to claim 1, wherein the control unit transports the paper in the second control at a second transport speed that is slower than the first transport speed that is the transport speed of the paper in the first control. The fixing device according to any one of the above.

The invention according to claim 7 is:
An image forming apparatus comprising: an image forming section that forms a toner image on a sheet of paper; and a fixing device according to any one of claims 1 to 6 .

The invention according to claim 8 is:
an image forming unit that forms a toner image on paper;
a fixing unit including a heating unit that sandwiches and heats the paper conveyed while holding a toner image; and a removal unit that removes toner from the heating unit; and a fixing unit that increases the temperature of the heating unit to a first temperature. a first control in which the sheet holding the toner image is sent to the heating section in a state in which the toner image is retained; and a second control in which the temperature of the heating section is set higher than the first temperature so that the toner held in the removal section is transferred to the heating section. A second time interval longer than the first time interval between adjacent sheets when the plurality of sheets of paper not holding a toner image are continuously conveyed in the first control in a state where the temperature is increased. The image forming apparatus is characterized in that it includes a control section that executes a second control for sending the image to the heating section at time intervals .

The invention according to claim 9 is:
Raising the temperature of the heating section constituting a fixing section, which includes a heating section that sandwiches and heats the paper conveyed while holding a toner image, and a removal section that removes toner from the heating section, to a first temperature. a first control execution unit that executes a first control to send the paper holding the toner image in the heated state to the heating unit;
A plurality of sheets of paper not holding a toner image while the temperature of the heating section is raised to a second temperature higher than the first temperature at which the toner held in the removing section moves to the heating section. A second control for sending the sheets to the heating unit at a second time interval longer than the first time interval between adjacent sheets when continuously conveying a plurality of sheets in the first control. 1 is a control program characterized by having a control execution section;

According to the fixing device according to claim 1 , the image forming apparatus according to claims 7 and 8 , and the control program according to claims 1 to 4 , when the second control for discharging the toner from the removal section onto the paper is not executed. Compared to this, toner stains on paper on which images are formed are suppressed.

Further, according to the fixing device according to claim 1 , the image forming apparatus according to claims 7 and 8 , and the control program according to claims 1 to 4 , in the second control, the same number of sheets is conveyed at the first time interval. Compared to the case where the toner is removed, the efficiency of collecting toner accumulated in the removal section is increased.

According to the fixing device of the second aspect, the time required to reach the second temperature is shortened compared to the case where the second heat amount is set from the start of the second control.

According to the fixing device of the third aspect, waste of power can be suppressed compared to a case where paper out is not taken into consideration.

According to the fixing device of the fourth aspect, the cooling period is shortened compared to the case where the paper is not fed within the cooling period.

According to the fixing device of the fifth aspect, wasteful operations can be avoided compared to the case where the second control is started without checking the presence or absence of paper.

According to the fixing device of the present invention, in the second control, the recovery efficiency of the toner accumulated in the removal section is increased compared to the case where the paper is transported at the same transport speed as in the first control.

1 is a schematic diagram showing the internal configuration of a printer as an embodiment of an image forming apparatus of the present invention. 2 is an enlarged schematic diagram of a fixing device that constitutes the printer of FIG. 1. FIG. FIG. 3 is an explanatory diagram of the action of a cleaning roller and a support roller. FIG. 3 is an explanatory diagram of a method for measuring adhesion force and toner cohesive force. FIG. 3 is an explanatory diagram showing the behavior of toner accumulated on a support roller under high temperature. FIG. 7 is a diagram showing changes over time in the temperature of the heating roller and the amount of toner transferred onto the heating roller in the ejection mode. It is a figure showing a flow chart showing control operation of a control part in discharge mode. FIG. 3 is an explanatory diagram of differences in toner behavior due to differences in strain rate.

Embodiments of the present invention will be described below.

FIG. 1 is a schematic diagram showing the internal configuration of a printer as an embodiment of the image forming apparatus of the present invention. This printer incorporates a fixing device as an embodiment of the present invention and a control program as an embodiment of the present invention.

This printer 20 has four image forming sections 50Y, 50M, 50C, and 50K arranged in one row. In these image forming units 50Y, 50M, 50C, and 50K, toner images are formed using toner of each color: yellow (Y), magenta (M), cyan (C), and black (K), respectively. Here, for explanations common to these image forming units 50Y, 50M, 50C, and 50K, the symbols Y, M, C, and K, which represent the distinction of toner colors, are omitted and the image forming units 50 are referred to as image forming units 50. . The same applies to other components other than the image forming section.

Each image forming section 50 is equipped with a photoreceptor 51. As this photoreceptor 51 rotates in the direction of arrow A in response to a driving force, an electrostatic latent image is formed on its surface, and a toner image is further formed by development.

A charger 52 , an exposure device 53 , a developing device 54 , a primary transfer device 62 , and a cleaner 55 are provided around each photoreceptor 51 provided in each image forming section 50 . Here, the primary transfer device 62 is placed at a position sandwiching an intermediate transfer belt 61, which will be described later, between the primary transfer device 62 and the photoreceptor 51. This primary transfer device 62 is an element provided in an intermediate transfer section 60, which will be described later.

The charger 52 uniformly charges the surface of the photoreceptor 51.

The exposure device 53 irradiates the uniformly charged photoreceptor 51 with exposure light modulated based on an image signal to form an electrostatic latent image on the photoreceptor 51 .

The developing device 54 develops the electrostatic latent image formed on the photoreceptor 51 with toner of a color corresponding to each image forming section 50 to form a toner image of each color on the photoreceptor 51.

The primary transfer device 62 transfers the toner image formed on the photoreceptor 51 onto an intermediate transfer belt 61, which will be described later.

The cleaner 55 removes residual toner and the like from the photoreceptor 51 after the transfer.

An intermediate transfer section 60 is arranged above the four image forming sections 50. This intermediate transfer section 60 is equipped with an intermediate transfer belt 61. This intermediate transfer belt 61 is supported by a plurality of rollers such as a driving roller 63a, a driven roller 63b, and tension rollers 63c and 63d. The intermediate transfer belt 61 is driven by a drive roller 63a and circulates in the direction of arrow B on a circulation path including a path along the four photoreceptors 51 provided in the four image forming sections 50. .

The toner images on each photoreceptor 51 are sequentially transferred onto the intermediate transfer belt 61 by the action of the primary transfer device 62 so as to overlap one another. The toner image transferred onto the intermediate transfer belt 61 is conveyed to the secondary transfer position T2 by the intermediate transfer belt 61. This secondary transfer position T2 is equipped with a secondary transfer device 71, and the toner image on the intermediate transfer belt 61 is conveyed to the secondary transfer position T2 by the action of the secondary transfer device 71. The image is transferred onto paper P. Conveyance of the paper P will be described later. Toner and the like remaining on the intermediate transfer belt 61 after the toner image has been transferred to the paper P is removed from the intermediate transfer belt 61 by the cleaner 64 .

A toner cartridge 100 containing toner of each color is provided above the intermediate transfer section 60. When the toner in the developing device 54 is consumed by development, toner is supplied to the developing device 54 from the toner cartridge 100 containing toner of the corresponding color through a toner supply path (not shown). The toner cartridge 100 is configured to be detachable from the device housing 90, and when it becomes empty, it is removed and a new toner cartridge 100 is installed.

Further, this printer 20 is equipped with a UI (user interface) 91. The UI 91 is composed of a touch panel type display screen, push buttons, etc., and transmits the user's instructions to the printer 20, and also displays messages from the printer 20 to the user.

Furthermore, this printer 20 is equipped with a control section 92. This control section 92 is responsible for controlling each section of this printer 20, including the control characteristic of this embodiment, which will be described later.

The paper tray 21 is equipped with an empty detection sensor 93. The empty detection sensor 93 detects that the paper P stored in the paper tray 21 has been consumed and the paper tray 21 has become empty.

To form an image on paper P, one sheet of paper P is taken out from paper tray 21 by pickup roller 23, separated into only one sheet by separation roller 24, and the separated one sheet P is transferred to transport roller 25. As a result, the paper is transported along the transport path in the direction of arrow C to the timing adjustment roller 26. The paper P that has been conveyed to the timing adjustment roller 26 reaches the secondary transfer position T2 by the timing adjustment roller 26 in synchronization with the timing at which the toner image on the intermediate transfer belt 61 reaches the secondary transfer position T2. The image is sent out toward the secondary transfer position. The paper P sent out by the timing adjustment roller 26 receives a toner image transferred from the intermediate transfer belt 61 by the action of the secondary transfer device 71 at the secondary transfer position T2. The paper P to which the toner image has been transferred is further conveyed in the direction of arrow D and passes through the fixing device 80 . The toner image on the paper P is heated and pressurized by the fixing device 80 and is fixed onto the paper P. As a result, an image consisting of the fixed toner image is printed on the paper P. The paper on which the toner image has been fixed by the fixing device 80 is further transported in the direction of arrow E by the transport roller 27, and is sent out from the paper ejection port 29 onto the paper ejection tray 22 by the paper ejection roller 28. This fixing device 80 corresponds to an example of the fixing device of the present invention. A detailed explanation of the fixing device 80 will be given later.

This printer 20 has a function of printing images on both sides of paper. When printing an image on both sides of a sheet of paper, first print the image on the first side of the sheet in the same manner as above, and then place the sheet on the paper output tray 22 to the halfway position shown by the dashed line in Fig. 1. Discharge. Then, when the paper is ejected to a halfway position, the paper ejection roller 28 rotates in the reverse direction. Then, the paper now advances in the direction of arrow F, passes through a reversing conveyance path sandwiched between two guide members 41 and 42, is further conveyed in the direction of arrow G by conveyance roller 31, and is again conveyed by timing adjustment roller 26. reach. Then, the paper is moved to the secondary transfer position so that the toner image for the second side on the intermediate transfer belt 61 reaches the secondary transfer position T2 in synchronization with the timing when the toner image for the second side reaches the secondary transfer position T2. sent towards. At the secondary transfer position T2, the toner image is transferred to the second side of the paper, and the paper after the transfer is conveyed in the direction of arrow D and fixed by the fixing device 80, further conveyed in the direction of arrow E, and then transferred to the paper ejection roller 28. As a result, the paper is then ejected onto the paper ejection tray 22. Images are printed on both sides of the paper discharged onto the paper discharge tray 22.

Here, the structure of the fixing device 80 will be explained.

FIG. 2 is an enlarged schematic diagram of a fixing device that constitutes the printer of FIG.

This fixing device 80 includes a heating roller 81 and a pressure belt 86. The heating roller 81 has a built-in halogen lamp 82 for heating. The pressure belt 86 is pressed against the heating roller 81 by a mechanism not shown, and the heating roller 81 and the pressure belt 86 rotate or circulate in the directions of arrows Q and R, respectively.

The paper P that has received the toner image transfer at the secondary transfer position T2 shown in FIG. The upper toner image is fixed on the paper P. During the fixing, toner may spill especially from the edge of the paper P, and the spilled toner may adhere to the heating roller 81 or the pressure belt 86. If the toner remains attached to the heating roller 81 or the pressure belt 86, the toner may adhere to the next sheet P and stain that sheet P.

Therefore, the fixing device 80 of this embodiment is provided with a structure that suppresses staining of the paper due to spilled toner. That is, the fixing device 80 includes a cleaning roller 83 that removes toner attached to the heating roller 81 from the heating roller 81, and a support roller 84 that receives and accumulates the toner from the cleaning roller 83. Similarly, this fixing device 80 includes a cleaning roller 87 that removes toner attached to the pressure belt 86 from the pressure belt 86, and a support roller 88 that receives and accumulates toner from the cleaning roller 87. We are prepared.

Here, the pair of heating roller 81 and pressure belt 86 corresponds to an example of a heating section according to the present invention. Further, the heating roller 81 corresponds to an example of the first rotating body according to the present invention, and the pressure belt 86 corresponds to an example of the second rotating body according to the present invention. Further, the pair of cleaning roller 83 and support roller 84 and the pair of cleaning roller 87 and support roller 88 each correspond to an example of the removing section according to the present invention. Further, the cleaning roller 83 corresponds to an example of the first cleaning section according to the present invention, and the cleaning roller 87 corresponds to an example of the second cleaning section according to the present invention. Furthermore, the support roller 84 corresponds to an example of the first accumulation section according to the present invention, and the support roller 88 corresponds to an example of the second accumulation section according to the present invention.

FIG. 3 is an explanatory diagram of the functions of the cleaning roller and the support roller. Although FIG. 3 shows the heating roller 81 and the cleaning roller 82 and support roller 83 on the heating roller 81 side, the following description also applies to the cleaning roller 87 and support roller 88 on the pressure belt 86 side. holds true.

A heating roller 81, a cleaning roller 82, and a support roller 83 are shown in each of FIGS. 3(A) to 3(C). When the adhesion forces of the heating roller 81, cleaning roller 82, and support roller 83 to the toner T are expressed by Fhr, Fcln, and Fspt, respectively,
Fhr < Fcln < Fspt
The surface properties of each roller 81, 82, 83 are adjusted so that the following holds true. The larger the value of this adhesion force, the easier it is for toner to adhere. A method for measuring the adhesion force will be described later with reference to FIG. 4.

FIG. 3A shows a state in which almost no toner has been accumulated on the support roller.

In this case, the toner T spilled onto the heating roller 81 is collected by the cleaning roller 82 and further transferred to the support roller 83 where it is accumulated.

FIG. 3(B) shows a state in which the support roller 83 is almost full.

Even in this state, if the cleaning roller 82 still has enough storage capacity, the toner T on the heating roller 81 is collected by the cleaning roller 82 . However, since the support roller is full, the collected toner T is accumulated on the cleaning roller 82.

FIG. 3C shows a state in which the accumulation has further progressed and the cleaning roller 82 is also full.

When not only the support roller 83 but also the cleaning roller 82 becomes full, the toner T on the heating roller 81 is no longer collected and remains on the heating roller 81. In this state, there is a risk that the toner T on the heating roller 81 may adhere to the paper P that is next conveyed to the fixing device 80 and stain the paper P.

If no particular measures are taken, the life of the cleaning roller 82 and support roller 83 will be reached when the state shown in FIG. Is required. The present embodiment is characterized in that the cleaning roller 82 and support roller 83, which are in the state shown in FIG. 3(C), are regenerated to a state close to that shown in FIG. 3(A) without being removed.

FIG. 4 is an explanatory diagram of a method for measuring adhesion force and toner cohesive force.

Place the paper on the pedestal and place the unfixed toner on top of the paper. Meanwhile, place the test piece at the tip of the probe. In this state, lower the probe, press the test piece against the unfixed toner, and then pull up the probe. The pressing force, pressing time, and temperature are designed values between each roller. Then, under these conditions, the force required to separate the test piece after melting the toner is measured. The force required for this separation is the adhesion force (kPa) of the toner to the test piece.

This test method can also be used to determine the cohesive force (kPa) of the toner. To examine the cohesive force of toner, paper is used as a test piece. This is done at various temperatures. Toner softens when the temperature rises, and melts when the temperature rises further. This greatly reduces the cohesive force of the toner. This embodiment attempts to regenerate the cleaning roller 82 and the support roller 83 by taking advantage of the fact that the toner melts under high temperature and its cohesive force is greatly reduced.

FIG. 5 is an explanatory diagram showing the behavior of toner accumulated on the support roller under high temperature.

Here, in addition to the adhesive force Fhr of the heating roller 81, the adhesive force Fcln of the cleaning roller 82, and the adhesive force Fspt of the support roller 83, the cohesive force of the toner is expressed as Ftn.

FIG. 5A shows a normal state in which toner collected from the heating roller is accumulated on the support roller. At this time, the cohesive force Ftn of the toner exceeds the adhesive force Fcln of the cleaning roller.

FIG. 5(B) shows a state in which the temperature is higher than that in FIG. 5(A) and the cohesive force Ftn of the toner has decreased. However, in FIG. 5B, the cohesive force Ftn of the toner still exceeds the adhesive force Fhr of the heating roller (Ftn>Fcln). At this time, the toner accumulated on the support roller has also moved to the cleaning roller. However, the toner has not yet moved to the heating roller.

FIG. 5C shows a state in which the temperature is higher than that in FIG. 5B, and the cohesive force Ftn of the toner is lower than the adhesive force Fhr of the heating roller (Ftn<Fhr). When the toner reaches a high temperature and Ftn<Fhr, the toner that was originally accumulated on the support roller becomes attached not only to the cleaning roller but also to the heating roller.

In this embodiment, by creating the state shown in FIG. 5(C) and passing the paper, the toner adhering to the heating roller is made to adhere to the paper, thereby reducing the amount of toner accumulated on the cleaning roller and support roller. , which attempts to regenerate the toner recovery ability on the heating roller.

FIG. 6 is a diagram showing temporal changes in the temperature of the heating roller and the amount of toner transferred onto the heating roller in the ejection mode. Here, the discharge mode is a mode in which a sequence is executed in which the toner accumulated on the support roller and the cleaning roller is transferred to the heating roller and attached to the paper.

Graph a in FIG. 6 shows the temperature change of the heating roller. When the heating roller is in a standby state, it is maintained at a standby temperature. During normal image formation, the heating roller, which is at the standby temperature, is heated to the fixing temperature and performs a fixing operation. The control of the control unit 92 shown in FIG. 1 to execute this normal fixing operation corresponds to an example of the first control and the third control according to the present invention. Further, the fixing temperature corresponds to an example of the first temperature according to the present invention. Further, the control of the control unit 92 shown in FIG. 1 to execute the discharge mode described below corresponds to an example of the second control according to the present invention.

In this ejection mode, the heating roller is heated to a ejection temperature higher than the fixing temperature. This discharge temperature corresponds to an example of the second temperature referred to in the present invention. When heating the heating roller at the standby temperature to the discharge temperature, the broken line in FIG. As shown in graph a', it takes time for the heating roller to reach the discharge temperature. Therefore, when the temperature of the heating roller at the standby temperature starts to rise, if the amount of heat is continued to be applied, the temperature will only rise to a higher temperature than the discharge temperature (third temperature in the present invention). The amount of heat (the first amount of heat according to the present invention) is applied, and halfway through, the amount of heat is switched to the amount of heat (second amount of heat) that is sufficient to finally reach the discharge temperature. By doing so, the temperature of the heating roller can be rapidly raised to the discharge temperature as shown in graph a, and the time required to complete the discharge mode can be shortened.

After the heating roller reaches the discharge temperature, it is maintained at that discharge temperature for a while. Graph b shows the amount of toner adhering to the heating roller. After maintaining the heating roller at the discharge temperature for a while, the heat of the heating roller is transferred to the cleaning roller and support roller, and the toner is dissolved, resulting in the state shown in Figure 5 (C) where the toner is even attached to the heating roller. .

During the time T1 in this state, the paper P is taken out from the paper tray 21 (see FIG. 1), and without forming a toner image, the paper P is passed through the fixing device 80 without forming a toner image. Then, the toner adhering to the heating roller is transferred to the paper. Here, a plurality of sheets (for example, five sheets) are passed through. During image formation, as many sheets of paper as possible are conveyed per unit time in order to improve productivity, but here, after conveying one sheet of paper, the time interval between sheets is reduced compared to when forming images. Empty and transport. This is because it is better to transfer the same amount of toner onto the paper after the toner on the heating roller is transferred from the heating roller to the paper, and then wait until the toner is transferred from the cleaning roller to the heating roller again before transporting the next paper. This is because the number of sheets of paper required for transfer is small. The time interval between sheets during image formation corresponds to an example of the first time interval according to the present invention, and the time interval between sheets during the ejection mode corresponds to an example of the second time interval according to the present invention.

After a sufficient amount of toner has been transferred to the paper in this manner, heating of the heating roller is stopped and the heating roller is cooled down until it returns to the standby temperature. Here, the paper is passed through the fixing device 80 even at time t2 during this cool-down period. When paper passes through the paper, heat is absorbed by the paper, and the cool-down period can be shortened, as shown by the broken line graph a'' in FIG. The toner remaining on the heating roller immediately before the cool-down regains its cohesive force as the toner cools down, is collected from the heating roller, and returns to the cleaning roller and then to the support roller.

FIG. 7 is a diagram showing a flowchart representing the control operation of the control unit in the discharge mode.

In this embodiment, the ejection mode is executed in response to an instruction from the user through the operation of the UI 91 (see FIG. 1). When the user is concerned about dirt on the paper on which the image has been formed, the user instructs execution of the ejection mode.

When execution of this ejection mode is started, first, the empty detection sensor 93 (see FIG. 1) detects whether or not paper P is stored in the paper tray 21 (step S01). If the paper tray 21 is empty, executing the ejection mode is not only meaningless but also wastes energy. Therefore, a notification that the paper tray 21 is empty is displayed on the screen of the UI 91 (step S02). ), then exit.

When it is found in step S01 that there is paper in the paper tray 21, the timer is turned on (step S03) and heating of the heating roller 81 is started. This timer is a timer for measuring the time until paper feeding. To raise the temperature of the heating roller 81, as described above, first, an amount of heat is applied that would raise the temperature to a higher temperature than the discharge temperature if the amount of heat was continued (step S04), and in the middle, The amount of heat is changed to an amount sufficient to finally reach the discharge temperature, and the discharge temperature is maintained (step S05). Then, after waiting for the timer to time up (step S06), the paper is passed through the fixing device 80. The purpose of waiting for the timer to expire is to wait for the toner to melt and adhere to the heating roller 81, as described above.

In passing the paper, first, it is determined whether or not a prescribed number of sheets (for example, 5) have already been passed (step S07). If the specified number of sheets have not been passed yet, it is determined whether or not there is no paper (paper tray 21 is empty) (step S08). This is because even if the specified number of sheets have not yet been passed, the paper may run out midway. If the paper is out of paper, a notification is displayed on the screen of the UI 91 to inform you that the paper is out and the process will proceed to cool down mode (step S09), cool down is started (step S10), and the process of this ejection mode is started. finish.

If it is determined in step S08 that the paper is not out of paper, a predetermined waiting time is waited to create a gap between the sheets (step S11), and then one sheet is passed (step S12).

After steps S07 to S12 are repeated a predetermined number of times, when it is determined in step S07 that the predetermined number of sheets have been passed, a cooldown is started (step S13). In this embodiment, paper passing is also performed during the cool-down period. Here, first, after the start of cool-down, it is determined whether or not a prescribed number of sheets (for example, two sheets) have been passed (step S14). If the prescribed number of sheets has not yet been passed, it is then determined whether the paper is out (step S15). If the paper is out of paper, a message is displayed on the screen of the UI 91 to inform that the cool-down process will take time because the paper is out (step S16), and the process of this ejection mode is ended. If it is determined in step S15 that the paper is not out of paper, one sheet is passed (step S17), and the process returns to step S14. When it is determined in step S14 that the prescribed number of sheets has been passed, the process of this ejection mode is ended.

This concludes the description of the first embodiment of the present invention, and next, the second embodiment of the present invention will be described.

FIG. 8 is an explanatory diagram of differences in toner behavior due to differences in strain rate.

Melted toner is a viscoelastic body, and its behavior may differ depending on the strain rate. Here, the strain rate refers to the speed of deformation (strain) when the molten toner is stretched. When the toner layer thickness is thick and the stretching speed is the same, the thinner the toner layer, the more the strain. If the speed is high and the toner layer thickness is the same, the faster the stretching speed, the higher the strain rate.

When the molten toner sandwiched between the heating roller and cleaning roller passes through a nip region where the heating roller and cleaning roller are in contact, it is stretched while adhering to both the heating roller and the cleaning roller. At this time, if the rotation speed of the heating roller or the like is high, the material will be stretched at a high strain rate.

FIG. 8(A) shows the behavior of molten toner when it is stretched at a high strain rate by high-speed rotation of a heating roller or the like. As shown in FIG. 8A, when the molten toner is stretched at a large strain rate, the molten toner has a strong tendency to separate from the heating roller and remain attached to the cleaning roller.

Moreover, FIG. 8(B) shows the behavior when the heating roller or the like rotates slowly and as a result is stretched with a small strain rate. As shown in FIG. 8B, when the strain rate is low, the molten toner tends to break off and adhere to the heating roller.

The second embodiment utilizes this phenomenon to only raise the temperature of the heating roller to the fixing temperature even in the ejection mode, and instead lowers the rotational speed of the heating roller etc. compared to when forming an image. This is intended to cause the molten toner to be ejected to the heating roller. That is, in the discharge mode, the rotational speed of the heating roller and the like is lowered, and the paper is slowly conveyed. This control for conveying the paper slowly corresponds to an example of the fourth control according to the present invention. The second embodiment can also be applied to a fixing device that does not have the ability to raise the temperature to a discharge temperature higher than the fixing temperature, as shown in FIG.

The above-mentioned FIG. 7 shows a flowchart of the ejection mode processing in the above-mentioned first embodiment, but here, referring again to the flowchart of FIG. 7, the ejection mode processing in the second embodiment will be explained. The process will be explained. However, the description of the same processing as in the first embodiment will be omitted.

In the case of the second embodiment, in steps S04 and S05 of FIG. 7, the temperature is raised to the fixing temperature and the fixing temperature is maintained. Furthermore, in the paper feeding in steps S12 and S17, the paper is transported at a lower speed than during image formation and passes through the fixing device.

Other steps in the second embodiment are the same as those in the first embodiment, and redundant explanation will be omitted.

Note that the first embodiment and the second embodiment may be combined as the third embodiment. That is, in the third embodiment, as in the first embodiment, the temperature of the heating roller is raised to a discharge temperature higher than the fixing temperature, and in the sheet feeding in step S12 and step S17, the temperature is increased as in the second embodiment. , the paper is conveyed at a lower speed than when forming the image and passes through the fixing device. According to the third embodiment, toner can be attached to paper more efficiently than either the first embodiment or the second embodiment.

In each of the above embodiments, a fuser consisting of a combination of a heating roller and a pressure belt has been described as an example, but the present invention is limited to a fuser consisting of a combination of a heating roller and a pressure belt. isn't it. The present invention can be applied to various types of fixing devices, such as a combination of a heating roller and a pressure roller, a combination of a heating belt and a pressure roller, or a combination of a heating belt and a pressure belt.

20 Printer 80 Fixing device 81 Heating roller 82 Cleaning roller 83 Support roller 86 Pressure belt 87 Cleaning roller 88 Support roller 91 UI (user interface)
92 Control unit 93 Sky detection sensor

Claims (9)

a fixing unit including a heating unit that sandwiches and heats the paper conveyed while holding a toner image; and a removal unit that removes toner from the heating unit; and a fixing unit that increases the temperature of the heating unit to a first temperature. a first control in which the sheet holding the toner image is sent to the heating section in a state in which the toner image is retained; and a second control in which the temperature of the heating section is set higher than the first temperature so that the toner held in the removal section is transferred to the heating section. A second time interval longer than the first time interval between adjacent sheets when the plurality of sheets of paper not holding a toner image are continuously conveyed in the first control in a state where the temperature is increased. A fixing device comprising: a control section that performs a second control to send the signal to the heating section at time intervals. At the start of the second control, the control section sets the amount of heat per unit time given to the heating section to a first amount of heat sufficient to raise the heating section toward a third temperature higher than the second temperature. A claim characterized in that, midway through, the amount of heat per unit time given to the heating section is changed to a second amount of heat, which is lower than the first amount of heat, so that the heating section is adjusted to the second temperature. 1. The fixing device according to 1. In the second control, the control section controls the heating section after feeding a predetermined number of sheets into the heating section, or if the paper runs out before reaching the specified number of sheets, at the time when the paper runs out. 3. The fixing device according to claim 1, further comprising a cooling period during which the fixing device is cooled. 4. The fixing device according to claim 3, wherein, in the second control, the control section feeds the paper to the heating section even during the cooling period. 5. The fixing device according to claim 1, wherein the control section does not start the second control if the paper runs out before starting the second control. 6. The control unit transports the paper in the second control at a second transport speed that is slower than the first transport speed that is the transport speed of the paper in the first control. The fixing device according to any one of the above. An image forming apparatus comprising: an image forming section that forms a toner image on paper; and a fixing device according to claim 1. an image forming unit that forms a toner image on paper;
a fixing unit including a heating unit that sandwiches and heats the paper conveyed while holding a toner image; and a removal unit that removes toner from the heating unit; and a fixing unit that increases the temperature of the heating unit to a first temperature. a first control in which the sheet holding the toner image is sent to the heating section in a state in which the toner image is retained; and a second control in which the temperature of the heating section is set higher than the first temperature so that the toner held in the removal section is transferred to the heating section. A second time interval longer than the first time interval between adjacent sheets when the plurality of sheets of paper not holding a toner image are continuously conveyed in the first control in a state where the temperature is increased. An image forming apparatus comprising: a control unit that executes a second control to send the data to the heating unit at time intervals. Raising the temperature of the heating section constituting a fixing section, which includes a heating section that sandwiches and heats the paper conveyed while holding a toner image, and a removal section that removes toner from the heating section, to a first temperature. a first control execution unit that executes a first control to send the paper holding the toner image in the heated state to the heating unit;
A plurality of sheets of paper not holding a toner image while the temperature of the heating section is raised to a second temperature higher than the first temperature at which the toner held in the removing section moves to the heating section. A second control for sending the sheets to the heating unit at a second time interval longer than the first time interval between adjacent sheets when continuously conveying a plurality of sheets in the first control. A control program comprising: a control execution section.

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